BVD prevalence down 84% since 2013

Back in 2013, it became compulsory for farmers operating in the Republic of Ireland to tissue tag test calves born on their farms for BVD (bovine viral diarrhoea).

During the first year of compulsory testing, the overall prevalence of PI (persistently infected) calves was 0.16% (3,806). However, according to data published by Animal Health Ireland (AHI) in its Annual Report 2017, the prevalence dropped to 0.10% (2,335) in 2017 – a reduction of approximately 84% when compared to 2013.

BVD
Animal-level prevalence (%) of PI calves born during each year of the programme. Source: Animal Health Ireland

AHI also reports that the prevalence of herds in which one or more calves had a positive or inconclusive result also decreased – moving from 3.3% (2,542) in 2016 to 2.0% (1,577) in 2017.

Prevalence (%) of herds with PI calves born during each year of the programme. Source: Animal Health Ireland

Relative to the position before the programme commenced, AHI states, it is estimated that the reduction in prevalence has generated a net benefit to the industry in 2017 alone of €75 million.

In addition, the total number of PIs still alive at the end of 2017 was only 53 compared to a figure of 292 at the end of 2016.

Moreover, AHI notes, the number of herds retaining PIs at the end of 2017 (still alive five weeks after the date of initial test) was 16, compared to a figure of 104 herds at the end of 2016 (still alive seven weeks after the date of initial test).

Map showing distribution of PI births during 2017. Source: Animal Health Ireland

The organisation credits a number of reasons for the improvements witnessed in terms of the number of PI calves still alive and the number of herds retaining PIs during 2017.

The reasons are outlined below:

  • The rebalancing of financial supports to increase the amount available for prompt removal, but reducing the time for which this was available;
  • Automatic restriction of herds retaining PIs for more than five weeks after the date of the initial positive result;
  • Notification of neighbouring herds;
  • Limiting confirmatory testing to blood samples collected by a veterinary practitioner and requirement for all herds with PI births to undertake a herd investigation funded under the Targeted Advisory Service on Animal Health (TASAH) within three weeks of the index case.

AHI also reports that number of herds awarded Negative Herd Status (NHS) had risen to over 71,000 (86%) from 65,000 (78%) of the 83,000 breeding herds in 2016.